The long-term objective for this project is to further refine and analyze the current clinical description of patients who present with complaints of disturbed olfactory ability. A psychophysical strategy which has been found useful in this regard is a confusion matrix analysis of the sense of smell for patients who present with such complaints. It is proposed to complete the acquisition of normative values for this matrix in which each odor is represented by a single chemical at an intensity such that its perception approximates the common natural substance with which it is associated. To further characterize the presenting complaint, an olfactory history algorithm has been developed, and it is proposed to compare the results from this algorithm to the behavioral measures of olfactory ability to determine how well they coincide with one another. A statistical model to evaluate the different patterns of responses found to occur within confusion matrices for patient populations was found to be lacking, and therefore it is proposed to develop and evaluate such a model to quantitatively discriminate among patient populations and normal controls. It is also proposed to evaluate an animal model developed as a mathematical analog of the clinical odorant confusion matrix. In this way, it should be possible to more critically examine the dysfunctions found in patient populations. Further proposed studies include the evaluation of the internal fine structure of the odorant confusion matrix with unidimensional scaling techniques and degradations of the matrix to simulate decrements of odorant access to the nasal airway.